Top your Butterbeer Blondies with this homemade butterscotch sauce for an extra delicious treat.
Combine brown sugar, corn syrup, and butter in a medium saucepan.
Cook over medium heat, stirring constantly until sugar is completely dissolved and the mixture comes to a full rolling boil.
Allow the mixture to boil, without stirring, for exactly 1 minute.
Remove from heat and let stand for 5 minutes.
Combine evaporated milk, baking soda, and vanilla in a bowl.
Stir into slightly cooled sauce.
Pour into a jar, cover, and refrigerate.